Among the wide variety of ink fountains on lithographic duplicating machines in use today, it is customary practice to supply the ink in the fountain by transferring the ink from a can, tube, or the like to the ink fountain of the machine. This manner of transferring the ink from the container to the fountain is usually effected manually and, therefore, oftentimes results in the operator's having ink-soiled fingers and clothing.
Additionally, because the ink in the fountain is exposed to the atmosphere, it is exposed to dust, dirt, lint and other foreign matter in the air which settles on the surface of the ink. As will be appreciated, this foreign matter in the ink fountain is likely to be passed through the ink train and onto the printing plate and often creates problems in attempting to obtain high quality duplicated copies.
Over the years, various attempts have been made to provide an ink package capable of preventing soiling of the hands during replenishment of ink in the ink fountains of lithographic duplicators and to prevent contamination of the ink.
One such device is shown in U.S. Pat. No. 3,561,360 and comprises a container removably mounted in an ink fountain and adapted to contain a supply of ink for application to an inking roller. One wall of the container is provided with outlet openings, and the container is adapted to cooperate with pressure applying means to expel the ink from the container via outlet openings onto the inking roller. The pressure applying means comprises a pusher continuously urged against a plunger by spring means to cause ink to be expelled from the container. The spring means is wound manually and, as it unwinds during operation, the plunger continues to force ink out of the container onto the inking roller.
Although the foregoing device provides a disposable ink container for maintaining the ink and the fountain substantially free from contamination, it does not provide for supplying and maintaining a substantially constant volume of ink on the inking roller by initiating and terminating the flow of ink from the container in response to the volume of ink on the inking roller as in the present invention.
Rather, the foregoing device relies merely on the urging of the spring means for continuously forcing the ink from the container without starting and stopping the flow of ink so as to maintain a uniform supply of ink on the inking roller as determined by the rate at which the ink is used in the duplicating operation. Hence, depending upon the amount and the rate at which the ink on the inking roller is utilized such a device, with provisions for only expelling and not stopping ink flow from the container, could well result in an oversupply of ink on the inking roller. Additionally, the various mechanisms and component parts required to dispense the ink from the container add considerably to the cost of the container and to the ink fountain designed to accept and coact with such a container.